Process of developing photographic pictures.



UNrrED STATES PATENT OFFICE.

ARTHUR EIOHENGRUN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBEN- FABRIKEN OF ELBERFELD (10., OF NEW YORK, N. Y., A CORPORATION OF NElV YORK.

PROCESS OF DEVELOPING PHOTOGRAPHIC PICTURES.

SPECIFICATION forming part of Letters Patent N 0. 716,396, dated December 23, 1902.

Application filed December 17, 1901. Serial No. 86,305- (No specimens.)

To aZZ whom it may concern. which, as is known, has a very good influence Be it known that I, ARTHUR EIOHENGRUN, on the developing process. Small quantities o doctor of philosophy, chemist, residing at Elof the acetone-alkali bisulfites suffice to renberfeld, Germany, (assignor to the FARBEN- der the developing-baths stable. For in- 5 FABRIKEN on ELBERFELD 00., of New York,) stance, the following formula may be emhave invented certain new and useful Imployed with good result: one part of pyrogalprovements in Processes of Developing Pho- 101, one part of acetone-alkali bisulfite, six tographic Pictures, of which the following is parts of potassium carbonate, and one huna specification. dred parts of water.

IO As it is known, neutral and acid sulfites of Having thus described my invention and alkalies are employed in photography as adin what manner the same is to be performed, mixtures to the photographic developing- What I claim as new, and desire to secure by baths in order to prevent an oxidation of the Letters Patent, isdeveloper which is employed; but the use of l. The herein-described process of develop- 15 sulfites entails great inconveniences, inasing photographic pictures consisting in submuch as their solutions cannot be kept and as jecting them to the action of a photographic the sulfites are decomposed by the action of developing bath containing additive comthe air. I have now found that these incon pounds from ketones and bisulfites, substanveniences in developing the photographic pictially as described.

20 tures can be obviated by employing instead 2. The herein-described process of developof the above-mentioned sulfites the additive ing photographic pictures consisting in subcompounds obtained from ketones and bisuljecting them to the action of a photographic 6o fites, especially the compounds which are predeveloping-bath containing acetone-alkali bipared from acetone and potassium or sodium sulfite having the formula 25 bisulfite, the so-called acetone-alkali bisul- OH fites having the following general formula:

oH, OH on/ SO M OH M M having the hereinbefore-defined meaning, 3o 3 3 substantially as described.

M meaning an alkaline metal, such as potas- In testimony whereof I have signed my sium or sodium. These additive compounds name in the presence of two subscribing withave the great advantage that they are readnesses. ily soluble in water and that even their con- 3 5 centrated solutions keep longin a well-corked bottle without decomposing. On adding al- Witnesses: kalies to the developing-baths containing ace- OTTO KGNIG, tone-alkali bisulfites the latter yield acetone, J. A. RITTERSHAUS.

ARTHUR EIoHENeRi'IN. 

